Dalhousie University’s library system was in a bind. Bound books, mostly out-of-date academic journals that had since been uploaded to online databases, had been piling up for years. At nearly 50,000 volumes, the library was running out of space, and shredding didn’t work. When builder and inventor David Cameron heard of the problem, he hoped to solve two problems at once, by using them to insulate an abandoned schoolhouse that’s now a community center focused on sustainability.